(LID)? Green Infrastructure (GI)€¦ · offering beautiful home landscaping. Rain gardens can be...
Transcript of (LID)? Green Infrastructure (GI)€¦ · offering beautiful home landscaping. Rain gardens can be...
Engineered + Nature Based Systems =
Successful Solutions
Preserving the existing capacity of the natural land is the absolute best
bang for your buck in terms of reducing stormwater and improving
community character. However, it’s not always possible to preserve
large areas of land, especially in urban settings. When communities need
to grow, they can incorporate smart growth techniques and layouts like
those discussed in Fact Sheet #2 that ensure engineered systems and
nature-based solutions work together.
Engineered systems include underground piping, outfalls, and catch basins
to intercept and transport stormwater. Nature-based solutions include
Low Impact Development (LID) best management practices such as rain
gardens and vegetated filter strips. Together, these systems offer a
comprehensive approach to managing stormwater in a way that’s smart
for your budget and your community character.
Minimizing
Imperviousness
with BMPs
Best Management Practices
(BMPs) can be installed in
both new and redevelopment.
Any time land will be
disturbed, find ways to
minimize impervious surfaces
and keep stormwater at its
source. Soil and vegetation break down pollutants and infiltrate water—
whether by the side of a road or from rooftops. By slowing the rate of
runoff, these BMPs also reduce flooding and associated financial and
health-related costs.
Trees and other plants also offer additional benefits such as air quality
protection, improved aesthetics, reduced energy use, and cost savings.
5 Tips for A Successful LID Project
1. Preserve the natural vegetation as much as
possible and use native species that will need
less maintenance
2. Keep slopes gentle to avoid erosion
3. Make sure the subsurface is highly
permeable—this may mean installing a
constructed subsurface
4. Get the community involved!
5. Visible, simple, and easily understood projects
are those that will be loved and successful!
What are Green Infrastructure (GI)
and Low Impact Development (LID)?
Green Infrastructure (GI) includes both
natural features such as forests and wetlands as well as engineered landscapes that mimic
these natural processes like a rain garden.
Low Impact Development (LID) works to preserve the natural landscape and
minimize impervious surfaces to keep stormwater close to the source and use it as
a resource rather than a waste product.
Together, LID and GI not only manage stormwater and improve groundwater
supplies, but also offer many free ecosystem services including cleaner air and water, flood
control, shade and energy savings, recreational opportunities, and enhanced property values and quality of life.
Preserving our existing GI is our first line of defense against climate impacts such as
increased storm frequency and intensities as well as achieving long-term cost savings.
Fact Sheet 3 of 5
Low Impact Development Best Management Practices
Bioretention strips filter parking lot runoff
#3 of 5
Low Impact Development Techniques R
ain
Barr
el &
Cis
tern
G
reen
Ro
of
Rain
Gard
en
Boston, MA: John W. McCormack US Post
Office and Courthouse. This 9,654 ft2 green
roof sits atop the EPA Region 1 Headquarters
on a historic 1933 building.
An example of 60-gallon rain barrels. Some
communities in MA offer a rain barrel program
that offers significant discounts to residents.
A small, slanted green roof in Craftsbury, VT.
This rain garden in Devens, MA gathers runoff
from a curb-less road and sidewalk to infiltrate
stormwater back into the ground while also
offering beautiful home landscaping. Rain
gardens can be made in any size and shape to
fit your location.
U.S. General Services Administration
EPA
Great American Rain Barrel Company
What is it? Planting vegetation on a roof so that rain can be taken up by plants
instead of running off. There are many types of green roofs and
they can serve as additional recreation space or simply a
stormwater storage area.
Cost $10-30/ft2 1, 2
Becomes up to 50% cheaper by the square foot as the square
footage exceeds 10,000 feet 3
Runoff Reduces runoff by 30-86%. 4
Additional
benefits
A 5,000 ft2 green roof sequesters 170 lbs of carbon/yr 2
Reduces heating and cooling costs for buildings by $6-8/ft2 3
Can extend life expectancies of roofs by more than double 1, 2, 3
But what
about...
Maintenance on green roofs entails general weeding and debris
removal, but since they’re watered by stormwater, which has
nutrients, they usually don’t need any fertilizer or irrigation.
What is it? A structure to store rooftop runoff and reuse it for landscaping and
other non-potable uses. There are many different styles, including
an above ground 50 gallon barrel or a below ground several
hundred or thousand gallon cistern.
Cost Average 50 gallon rain barrel costs around $100
Cisterns can be more expensive, depending on the size
Runoff At scale, cisterns can store 100% of rooftop runoff except in
extreme storms.
Additional
benefits
A one-inch rainstorm generates 623 gallons of stormwater per
1,000 square foot of roof that can be collected
Water can be used to landscape in hot summer months, saving
water costs
But what
about... Installation is a cinch – simply attach a downspout elbow to
divert rainwater from your lawn or driveway into the barrel.
When you’re ready to harvest the water, just attach a hose and
go! Above ground cisterns can be just as easy, though below
ground cisterns require more work for siting and installation.
What is it? A depression in the ground to filter stormwater that is filled with
highly permeable subsurface and water-loving vegetation. May have
an engineered overflow drain system as well.
Cost Costs about $2-12/ft2 5
Costs about $200/yr in labor for maintenance 6, 7
Runoff Reduces runoff by 90%. 8
Additional
benefits
Reduces pollutants, including Nitrogen, Phosphorus, metals,
and TSS by 65-90% 8
Improves aesthetics
But what
about...
Ownership and maintenance can be held by the individual
residential property owners, homeowners’ associations, or by
local public works. If outside entities need to be on private prop-
erty to maintain bioretention such as rain gardens, be sure to
include this in deeds so that homeowners understand what is
their responsibility and what is the municipality’s.
Perm
eab
le P
avem
en
t
This parking lot in Narragansett, RI shows
traditional asphalt on the left, where puddles
have formed, and permeable pavement on the
right, where it has soaked through.
Sto
rmw
ate
r W
etl
an
d
This insert shows a University of NH parking
lot one hour after plowing. The inset photo
shows a close up of the permeable pavement
section of the lot at the same time.
These Devens, MA homes have met the
required 20’ wide emergency vehicle access in
a unique way. They installed 12’ of pavement
and 8’ of permeable grass pavers to the left to
minimize pavement without compromising
safety.
This stormwater wetland in Leominster uses
the land’s natural capacity to filter and
infiltrate water.
Rain gardens and stormwater wetlands are just two types of bioretention
systems, which allows the landscape to filter pollutants and infiltrate
stormwater into the ground. These systems give excess water a place to
go, and reduce flooding and infrastructure damage.
Other systems include vegetated parking lot medians, roadside swales or
“country drainage,” and curb cuts, which take stormwater from streets
and filter it into a roadside rain garden or tree box.
Horsley Witten Group
National Asphalt Pavement Association
Massachusetts Watershed Coalition
Devens Enterprise Commission
Other Bioretention Systems
What is it? Permeable, or porous, pavement or concrete allows water to
infiltrate the driving surface to reduce stormwater runoff,
eliminate puddles, and increase groundwater recharge.
Cost Costs range from $10-12ft2 installed. 7
Runoff Can infiltrate as much as 70-80% of annual rainfall.
Additional
benefits
Reduces the amount of land needed for stormwater
management
Reduced flood risk may increase property value by 2-5% 2
Massachusetts communities typically spend over $100,000
annually on salting. 9 Areas with permeable pavement can
reduce salt use by as much as 75%, leading to enormous
cost savings 10 and reduced salt pollution
But what
about...
Winter weather is no trouble for permeable pavement. In
fact, studies at the University of NH Stormwater Center have
found that before icing, precipitation melts into the ground and
unsalted porous pavement offers a shorter stopping distance
than salted traditional pavement. This improves safety and can
reduce salting by 75%, saving money as well.
What is it? A type of detention basin where runoff is diverted into an engi-
neered, shallow wetland area to temporarily store water. Must
be used with another BMP that filters sediment. Smaller, pocket
wetlands fed only by stormwater can be used when less space
is available.
Cost Costs range from $25,000-30,000 per acre of impervious
area treated 6, 7
$1,500-2,000/yr in labor for maintenance and
vegetation control 6, 7
Runoff Can infiltrate 100% of peak flow when built to size.
Additional
benefits
Total Suspended Solids (TSS) - 80% with pretreatment 8
Reduces pollutants, including Nitrogen (20-55%), Phospho-
rus (40-60%), metals (up to 85%), and pathogens (up to
75%) 8
But what
about...
Building near natural wetlands is regulated under the
Wetlands Protection Act. However, constructed storm-
water wetlands are not so strictly regulated and additional
permits are not required for ongoing maintenance.
What is it
& benefits
Instead of having a wide road with a large paved circle at the end,
the circle can be vegetated to increase infiltration. Alternatively, the
road could make a loop and be enclosed with vegetated area that’s
perfect for community spaces.
But what
about...
Emergency vehicles and plow trucks need space to turn around,
which narrower roads and alternative cul-de-sac options still
provide. National Fire Protection Association requires a 20’ wide
passage for fire trucks.12 However, communities have met this
requirement in innovative ways. Some homes in Devens, MA have
rear garages on 12’ of pavement bordered by 8’ of grass pavers on
the side. This structure is still heavy weight bearing and the
combined 20’ roadway was accepted by the local fire department.13
LID Site Design: Less Pavement, More Savings
By reducing the amount of pavement, communities are not only reducing their impervious
surface and allowing more space for stormwater infiltration, but also realizing a huge cost
savings. Traditional paving costs about $6ft2. Reducing just a short two-mile road from 28’
wide to 20’ equates to a savings of over $500,000. Less pavement also means reduced
maintenance costs, including plowing, salting, and sweeping.
What is it
& benefits
Designing and installing 10’ or 12’ lanes on neighborhood roads
reduces the amount of impervious surface and enhances the land’s
ability to infiltrate water and pollutants.
But what
about...
Safety should always be a top concern, which is why narrow roads
are a smart idea. Studies have shown that 10’ lanes are as safe as –
if not safer than – wider lanes.11 When roads are narrower, drivers
go slower, pay closer attention to the road, and have fewer
accidents. Street-lined trees that provide a shaded lane and homes
closer to the roadways also enhance these safety benefits. Narr
ow
er
Ro
ad
s S
hare
d D
rivew
ay
Alt
ern
ati
ve
Cu
l-d
e-s
acs
This narrow road in Devens, MA easily
fits two lanes of traffic and offers
room for a vegetated buffer, sidewalk,
and street trees.
An alternative cul-de-sac design that
allows for recreational space as well as
a place to improve stormwater
infiltration.
Cyburbia
This project was funded by an agreement (CE96184201) awarded by the Environmental Protection Agency to the New England Interstate Water Pollution Control
Commission on behalf of the Narragansett Bay Estuary Program. Although the information in this document has been funded wholly or in part by the United States Environmental Protection Agency under agreement CE96184201 to NEIWPCC, it has not undergone the Agency’s publications review process and therefore, may not necessarily reflect the views of the Agency and no official endorsement should be inferred. The viewpoints expressed here do not necessarily represent those
of the NBEP, NEIWPCC, or U.S. EPA nor does mention of trade names, commercial
This shared driveway in the Pinehills in
Plymouth, MA provides easy access to
garages, plenty of parking, and less
impervious surface. Retention of
mature trees also offers privacy.
Learn More For more information, including all five fact sheets, a local land use regulatory review template,
presentations, references, and related resources check out www.massaudubon.org/
This project is funded in part by the
Massachusetts Environmental Trust.
Learn more about the Trust and the programs it supports through specialty license plate offerings at www.mass.gov/eea/met
What is it
& benefits
Instead of each home having a separate driveway from the street,
shared driveways that then split to each home offer access to
homeowners while still reducing impervious surfaces and increasing
stormwater infiltration.
But what
about...
Marketable homes with shared driveways don’t deter potential
buyers. In fact, homes in Concord and Plymouth with shared
driveways and parking still brought high value and sold quickly –
including during the 2008 recession. 14, 15